The present invention concerns a programmable cylinder lock, namely a lock comprising devices intended to allow, through a change operation, to modify the former lock codification in order to adjust the lock for being operated by a key different from the key to which the lock was formerly adapted.
More particularly, the invention concerns improvements in a kind of programmable cylinder lock which is known from the European Patents Nos. 0.226.252 and 0.900.310.
The kind of locks to which applies the present invention is a lock with a programming device, which comprises a stator, a bore provided in said stator, a rotor rotatably mounted in said stator bore and a keyhole hollowed in said rotor, and wherein the programming device comprises in the stator a longitudinal groove made in said stator bore and a series of stator seats, which in case can contain counterpins and the respective springs, and comprises in the rotor:—a series of first seats intersecting said keyhole and a series of second seats parallel to said first seats;—a first slot and a second slot, orthogonal with respect to said seats and parallel to the rotor axis;—a series of key followers inserted with longitudinal and transversal mobility in said first rotor seats for cooperating with the conformations of a key inserted into said keyhole, each key follower having on one side some projections and on the other side an element for sliding engagement, and having an associated spring;—a series of locking pins slidingly inserted in said second rotor seats corresponding to said stator seats and possible counterpins and having a series of first recesses facing said projections of the key followers and a series of second recesses turned on the side opposite said key followers;—a stop bar inserted in said first rotor slot, having projections facing said second recesses of the locking pins, and a projection turned on the side opposite said locking pins and suitable for cooperating with said stator groove for allowing an outward displacement of the stop bar;—first springs associated to said stop bar and stressing the same outwards;—a change bar, inserted in said second rotor slot, having slidable engagement elements engaged with said sliding engagement elements of the key followers, and having a projection turned on the side opposite the key followers and suitable for cooperating with said stator groove for allowing an outward displacement of the change bar;—said component parts being coordinated in such a way that said projections of the stop bar engage said second recesses of the locking pins when the projection of the stop bar does not correspond to said stator groove, and disengage therefrom when the stop bar corresponds to said stator groove, displaces outwards under action of said first springs and determines for the lock a position for insertion and retraction of the key, whereas said key followers engage said second recesses of the locking pins when the projection of the change bar does not correspond to said stator groove and disengage therefrom when said change bar corresponds to said stator groove, displaces outwards by dragging with them the key followers by action of the respective sliding engagement elements, and determines for the lock a position of key change in which said key followers are disengaged from said locking pins and allow replacing the key with consequent different programming of the lock.
The document US 2005/217330 A1 is regarded an the closest prio art and partially corresponds to the preamble of claim 1.
A general drawback of the known programmable locks is that, if the key intended for programming the lock is inserted in incomplete manner, the lock receives a faulty programming which, then, it is not easy to correct.
Therefore there is a request for adding a protection against faulty programming due to incomplete key insertion.
In addition, in most known programmable locks there are also provided second springs associated with said change bar, which springs stress the change bar outwards whereby, when the lock is situated in the change position, the protrusion of the change bar engages the stator groove, the change bar displaces outwards, cancels the lock programming and allows a new programming. Therefore, the change bar displaces automatically outwards, by disengaging the key followers from the locking pins, each time the key is brought in the change position.
However, it is needed to prevent that the lock loses its programming by chance if the key is extracted when it is in the change position, even if the user was not intended to change the programming. To this aim, according to the document EP 0.900.310 there is provided, near the outer end of rotor, a fork ring engaging a recess of the key and preventing its extraction when the key is not in the position for insertion and extraction. In this case, the change of programming is possible only by using a special change key whose shape is such that it is not retained by the fork ring.
All this complicates the lock structure and involves complicated actions, difficulties and obstacles for the user who is intended to modify the lock programming. Moreover, because a special key is needed for effecting the change, it is not possible to arrange the lock for using normal keys available in commerce, a possibility which would be of great technical and commercial interest.